In the second year of this N.I.H. research project, we propose to further evaluate the effects of vasoactive agents upon splanchnic viscera. Specifically, we will address questions with regard to the effects of vasoactive agents on nutrient blood flow to specific organs such as small bowel, stomach, liver, large bowel, spleen and pancreas. The question of whether the microcirculatory events correlate with the changes in these organs' total blood flow in response to various pharmacologic agents used clinically to control gastrointestinal hemorrhagic or ischemic lesions in man will be investigated. In addressing these questions, we will evaluate nutrient blood flow utilizing arteriovenous oxygen differences and radioactive microspheres. Liver function will also be evaluated using indocyanine green dye clearance. These data will provide insight into the questions of whether one can selectively increase or decrease nutritive blood flow utilizing pharmacologic agents. In addition, we will have a better understanding of possible risk of producing tissue damage through the effects of these pharmacologic agents upon the microcirculation of specific splanchnic organs.